Be warned: The next version of iOS will feature a major but hidden change

Be honest. When you learn that a new version of iOS is available, do you back up all of your data and files to Apple's cloud before installing it?

With the next version of iOS, it will be imperative that you do. That's because with this version, Apple is introducing a new file system, called Apple File System, that replaces the ancient 30-year-old file system, HFS+, that iOS currently uses.

Your iOS will automatically convert to the new file format, and it is not compatible with the old format. If some glitch happens during the install, some of your files stored on the device could be toast.

The current version of iOS is 10.2.1. The next big update is 10.3, and even though it is not promoted as iOS 11, it is still considered a major update. Developers have been playing with the beta version since the last week of February, and the general speculation is that it could be available by the end of March.

For the most part, developers love the new file system. It will allow them to do all kinds of new things for their apps that HFS+ didn't like include strong encryption, better manage large chunks of data, improve time stamps, save space, and help protect files from crashes. All good things.

But there is a downside that has some developers concerned, one developer told Business Insider.

iOS 10.3 will "automatically convert all the data on a device to APFS," this developer told Business Insider, referring to Apple File System. "The format the data is stored in will be changed. The data itself should still be there, but with the format changed."

So, if something goes wrong with converting each file stored on the device to this new format, even if you have a backup, you can't just transfer the file over from a previous version. The new iOS won't be able to read it. So if an app tanks, or if all your data is missing, the app developer may not be able to help you.

APFS will eventually be available on all Apple devices, and Apple will offer an easy painless, nontechnical method to upgrade and convert. But there is no method for converting anything back from APFS to HFS+, Apple says. So if you upgrade to APFS and something goes wrong and you want the old version of iOS back, you'll have to reformat your drive to get the old file system back, which will delete all of your files on your device.

That's not a huge problem if you have a full backup. It's not great if your phone gets bricked somehow and you didn't back up.

We understand that Apple will be warning people to back up their devices before installing 10.3, though we also understand that this warning won't necessarily stand out. It could look like the ordinary warning that many of us, having upgraded iOS and apps many times before, tend to ignore.

To its credit, Apple is fanatically concerned about making mistakes that cause people to lose any data. One Apple engineer once told us that the feeling there was, "What if we lost one photo and it was the only photo of grandma that you had?"

So, if problems occur with this update, they most likely won't be widespread.

That said, when the company does bork things up, it isn't good about fessing up. We saw that with the mysterious 30% bug that shut off people's phones when the battery hit 30%. It appeared with a software update, yet Apple told people it was a faulty-battery problem, and then it also vanished with the 10.2.1 update.

So make a mental note right now. When it comes to iOS 10.3, do a full backup first.